Epidemiologist Warns CDC’s Relaxed School Guidance Doesn’t Address Two Primary Forms of Transmission


Dr. Angela Ulrich weighed in on the decision to ease social distancing in classrooms

The decision by the Centers for Disease Control and Prevention to ease school pandemic safety guidelines has become the subject of much debate among health professionals, teachers and parents alike. Earlier this month, the CDC reduced its recommended distance between students in a classroom from 6 feet to 3 feet as long there is universal masking.

Epidemiologist Angela Ulrich warned the new CDC guidance doesn’t address one of these primary forms of transmission: time. She said that students and teachers are spending extended time together, often hours over the course of several days, giving more opportunities for disease to spread. She added that this is especially concerning in light of the spread of variants like B117, which originated in the U.K. In some states, such as Florida and California, the variant already accounts for 25% of cases

“When we think about an exposure to a person who is infected that is capable of causing infections, we think about concentration and time,” Ulrich, who is an assistant professor at the University of Minnesota School of Public Health, told KCM. “That is to say that infection is dependent on concentration and time, particularly as aerosols diffuse across a given space over time.”

The CDC did not immediately respond to a request for comment from KCM.

The CDC’s revised school rules were primarily driven by new research. The CDC published three new studies, offering further evidence that schools can operate safely as long as students maintain at least 3 feet and mask use is widely adopted, along with other prevention measures. Three feet is also the minimum distance that is endorsed by the American Academy of Pediatrics and the World Health Organization

“CDC is committed to leading with science and updating our guidance as new evidence emerges,” said CDC Director Rochelle P. Walensky on the release of the new rules.

Specifically, the latest recommendation is for all K-12 students, but there is some nuance for upper grade levels. The CDC advised middle school and high schools to keep students at least 6 feet apart in communities where transmission is high. 

The change allows more students to be inside classrooms — something Ulrich said should have been taken more seriously. She warned increasing capacity in classrooms could change the dynamics of the disease, potentially increasing the risk of exposure to the coronavirus. 

“Decreasing the guidance from 6 to 3 feet that in essence doubles the capacity of a room and so, you’re increasing the probability that there might be someone or multiple people who are infected and then the number of people who are potentially exposed to that,” she said. 

The CDC’s revised guidance comes amid a massive push to get kids back in the classroom. For many schools, the 6-feet guidance posed a major obstacle towards how many students schools could accommodate. This forced some schools to remove desks and stagger schedules in order to keep children apart. 

While the revised guidance is less demanding for schools, some teachers have spoken out against the change. The nation’s second-largest teachers union wrote a letter to Walensky and Secretary of Education Miguel Cardona questioning the decision and studies the agency based its action on.

“We are not convinced that the evidence supports changing physical distancing requirements at this time. Our concern is that the cited studies do not identify the baseline mitigation strategies needed to support 3 feet of physical distancing,” wrote Randi Weingarten, who is the president of the American Federation of Teachers.

In addition to proper masking, the CDC emphasized the importance of proper ventilation, though this might be challenging given that some schools have classrooms that don’t even have windows. This is where schools might have to get creative and think outside-of-the-box, such as holding classes in gyms or outside when the weather is nice, according to Ulrich.

The concept of holding outdoor classes is nothing new, of course, and was implemented nearly a century ago in New York City when tuberculosis was taking a toll on U.S. cities.

This is why coronavirus vaccinations will become even more crucial for the return of in-person classes. On March 2, the Department of Health and Human Services issued a directive, instructing all states immediately make teachers, school staff, and child care workers eligible for vaccinations.

The vaccination of kids will also play a key role in the return of in-person classes and keeping everyone safe —  both inside and outside school settings. The nation’s top infectious disease expert, Dr. Anthony Fauci, told lawmakers that the U.S. won’t be able to achieve herd immunity until children can get vaccinated.

Though researchers have already started testing the vaccine on children, Ulrich doesn’t expect a broader rollout to happen anytime soon. 

“Kids are the most precious thing that we have and we’re careful with vaccines for every population that it goes into, especially for kids,” she said. “It won’t be made available until we know that it’s both safe and effective.”

But encouraging everyone to get the vaccinations, especially children, could be the next obstacle for schools, according to the epidemiologist, given some of the hesitancy around the vaccine, not to mention the presence of the anti-vaxxer movement that began long before the pandemic. 

“We need to really think carefully about what policies we put into place that could encourage people who are potentially hesitant or don’t have their heels dug in too far to get vaccinated,” Ulrich said. 

There’s also just the general decline in routine vaccine rates in some pockets of the country. In Michigan, fewer than half of infants age 5 months and younger are up-to-date on recommended vaccinations, according to a CDC study published last year.

The same is also true for some urban areas. In New York City, the number of vaccine doses given to children 2 years and older dropped by 91% from March 23 to May 9, 2020, during the early months of the pandemic.

As far as whether the drop in broader immunization will take a toll, only time will tell.

“As students start going back to school, germs are going to start spreading again and there is that concern that will we have dropped below the herd immunity thresholds for these other diseases that we haven’t seen for quite a while among kids,” Ulrich said. 

Written and reported by Tess Bonn.